package com.bjc.nio;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * @program: nettypro
 * @description:
 * Scattering:将数据写入到buffer时，可以采用buffer数组，一次写入【分散】
 * Gathering：从buffer读取数据时，可以采用buffer数组，依次读
 * @author: bjc
 * @create: 2021-09-03 22:09
 */
public class ScatteringAndGatheringTest {

    public static void main(String[] args) throws Exception {
        //使用ServerSocketChannel 和 SocketChannel网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);
        //绑定端口到socket，并启动
        serverSocketChannel.socket().bind(inetSocketAddress);
        //创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);
        //等客户端连接（telnet）
        SocketChannel socketChannel = serverSocketChannel.accept();
        //假定从客户端接收8个字符
        int messageLength = 8;
        while (true){
            int byteRead = 0;
            while (byteRead<messageLength){
                long l = socketChannel.read(byteBuffers);
                //累计读取的字节数
                byteRead+= l;
                System.out.println("累计读取的字节数byteRead="+byteRead);
                //使用流打印，看看当前的这个buffer的position和limit
                Arrays.asList(byteBuffers).stream().
                        map(buffer->"position="+buffer.position()+",limit="+buffer.limit())
                        .forEach(System.out::println);
            }

            //将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(ByteBuffer::flip);

            //将数据读出显示到客户端
            long byteWirte = 0;
            while (byteWirte < messageLength){
                long l = socketChannel.write(byteBuffers);
                byteWirte+= l;
            }
            //将所有的buffer进行clear
            Arrays.asList(byteBuffers).forEach(ByteBuffer::clear);

            System.out.println("byteRead:="+byteRead+",byteWrite="+byteWirte+",messageLength="+messageLength);
        }
    }
}
